AAPM’s TG-51 protocol for clinical reference dosimetry of high-energy photon and electron beams contains many details to which we should pay close attention when performing necessary measurements for the calibration of high-energy beams. One such measurement is calculating the polarity correction factor (Ppol) for ionization chambers used in electron beam dosimetry. Since polarity effects vary with beam quality and other conditions (such as cable position), one must correct for these effects by making measurements each time clinical reference dosimetry is performed. To correct an ion chamber’s raw reading for polarity effects it is necessary to take readings with both polarities applied and tabulate Ppol by the following equation: Read more

The DVS-HFT (Dose Verification System) is the first wireless and implantable dosimeter system. The device was developed by Sicel Technologies, Inc. In March 2009, Sicel Technologies, Inc announced that it had received clearance from the U.S. Food and Drug Administration to begin marketing the DVS-HFT for measuring actual radiation dose at the tumor site when treating breast and prostate cancer patients undergoing external beam radiation therapy. The company also makes and markets OneDose, patient dosimetry verification systems specifically designed for radiation oncology therapy (we use them in our cancer center). DVS-HFT is specifically used for higher radiation doses over fewer treatments. This technique is called Hypo-Fractionated Therapy (HFT) and is highly effective in treating certain tumors.

“The DVS-HFT is an important advance in hypo-fractionated therapy, because physicians can now confidently determine the prescribed dose has been accurately delivered throughout the course of treatment, which is a key determinant in the long-term successful treatment of a tumor,” said Arnold Malcolm, MD, Associate Professor Vanderbilt Center for Radiation Oncology. “This device may actually accelerate the use of hypo-fractionated protocols, like those being adopted for treatment of prostate cancer, which may offer benefits across the healthcare spectrum.”